1// Unicode utilities -*- C++ -*-
2
3// Copyright The GNU Toolchain Authors.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/bits/unicode.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{format}
28 */
29
30#ifndef _GLIBCXX_UNICODE_H
31#define _GLIBCXX_UNICODE_H 1
32
33#if __cplusplus >= 202002L
34#include <array>
35#include <bit> // bit_width
36#include <charconv> // __detail::__from_chars_alnum_to_val_table
37#include <string_view>
38#include <cstdint>
39#include <bits/stl_algo.h>
40#include <bits/stl_iterator.h>
41#include <bits/ranges_base.h> // iterator_t, sentinel_t, input_range, etc.
42#include <bits/ranges_util.h> // view_interface
43
44namespace std _GLIBCXX_VISIBILITY(default)
45{
46_GLIBCXX_BEGIN_NAMESPACE_VERSION
47namespace __unicode
48{
49 // A Unicode code point that is not a high or low surrogate.
50 constexpr bool
51 __is_scalar_value(char32_t __c)
52 {
53 if (__c < 0xD800) [[likely]]
54 return true;
55 return 0xDFFF < __c && __c <= 0x10FFFF;
56 }
57
58 // A code point that can be encoded in a single code unit of type _CharT.
59 template<typename _CharT>
60 constexpr bool
61 __is_single_code_unit(char32_t __c)
62 {
63 if constexpr (__gnu_cxx::__int_traits<_CharT>::__max <= 0xFF)
64 return __c < 0x7F; // ASCII character
65 else
66 return __c < __gnu_cxx::__int_traits<_CharT>::__max
67 && __is_scalar_value(__c);
68 }
69
70 // Based on https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2728r6.html#add-the-transcoding-iterator-template
71
72 struct _Repl
73 {
74 constexpr char32_t
75 operator()() const noexcept
76 { return 0xFFFD; }
77 };
78
79 struct _Null_sentinel_t
80 {
81 template<input_iterator _It>
82 requires default_initializable<iter_value_t<_It>>
83 && equality_comparable_with<iter_reference_t<_It>, iter_value_t<_It>>
84 friend constexpr auto
85 operator==(_It __it, _Null_sentinel_t)
86 { return *__it == iter_value_t<_It>{}; }
87 };
88
89 template<typename _FromFmt, typename _ToFmt,
90 input_iterator _Iter, sentinel_for<_Iter> _Sent = _Iter,
91 typename _ErrorHandler = _Repl>
92 requires convertible_to<iter_value_t<_Iter>, _FromFmt>
93 class _Utf_iterator
94 {
95 static_assert(forward_iterator<_Iter> || noexcept(_ErrorHandler()()));
96
97 public:
98 using value_type = _ToFmt;
99 using difference_type = iter_difference_t<_Iter>;
100 using reference = value_type;
101 using iterator_concept
102 = std::__detail::__clamp_iter_cat<__iter_category_t<_Iter>,
103 bidirectional_iterator_tag>;
104
105 constexpr _Utf_iterator() = default;
106
107 constexpr
108 _Utf_iterator(_Iter __first, _Iter __it, _Sent __last)
109 requires bidirectional_iterator<_Iter>
110 : _M_first_and_curr{__first, __it}, _M_last(__last)
111 {
112 if (_M_curr() != _M_last)
113 _M_read();
114 else
115 _M_buf = {};
116 }
117
118 constexpr
119 _Utf_iterator(_Iter __it, _Sent __last)
120 requires (!bidirectional_iterator<_Iter>)
121 : _M_first_and_curr{__it}, _M_last(__last)
122 {
123 if (_M_curr() != _M_last)
124 _M_read();
125 else
126 _M_buf = {};
127 }
128
129 template<class _Iter2, class _Sent2>
130 requires convertible_to<_Iter2, _Iter> && convertible_to<_Sent2, _Sent>
131 constexpr
132 _Utf_iterator(const _Utf_iterator<_FromFmt, _ToFmt, _Iter2, _Sent2,
133 _ErrorHandler>& __other)
134 : _M_buf(__other._M_buf), _M_first_and_curr(__other._M_first_and_curr),
135 _M_buf_index(__other._M_buf_index), _M_buf_last(__other._M_buf_last),
136 _M_last(__other._M_last)
137 { }
138
139 [[nodiscard]]
140 constexpr _Iter
141 begin() const requires bidirectional_iterator<_Iter>
142 { return _M_first(); }
143
144 [[nodiscard]]
145 constexpr _Sent
146 end() const { return _M_last; }
147
148 [[nodiscard]]
149 constexpr _Iter
150 base() const requires forward_iterator<_Iter>
151 { return _M_curr(); }
152
153 [[nodiscard]]
154 constexpr value_type
155 operator*() const { return _M_buf[_M_buf_index]; }
156
157 constexpr _Utf_iterator&
158 operator++()
159 {
160 if (_M_buf_index + 1 == _M_buf_last && _M_curr() != _M_last)
161 {
162 if constexpr (forward_iterator<_Iter>)
163 std::advance(_M_curr(), _M_to_increment);
164 if (_M_curr() == _M_last)
165 _M_buf_index = 0;
166 else
167 _M_read();
168 }
169 else if (_M_buf_index + 1 < _M_buf_last)
170 ++_M_buf_index;
171 return *this;
172 }
173
174 constexpr _Utf_iterator
175 operator++(int)
176 {
177 auto __tmp = *this;
178 ++*this;
179 return __tmp;
180 }
181
182 constexpr _Utf_iterator&
183 operator--() requires bidirectional_iterator<_Iter>
184 {
185 if (!_M_buf_index && _M_curr() != _M_first())
186 _M_read_reverse();
187 else if (_M_buf_index)
188 --_M_buf_index;
189 return *this;
190 }
191
192 constexpr _Utf_iterator
193 operator--(int)
194 {
195 auto __tmp = *this;
196 --*this;
197 return __tmp;
198 }
199
200 [[nodiscard]]
201 friend constexpr bool
202 operator==(_Utf_iterator __lhs, _Utf_iterator __rhs)
203 requires forward_iterator<_Iter> || requires (_Iter __i) { __i != __i; }
204 {
205 if constexpr (forward_iterator<_Iter>)
206 return __lhs._M_curr() == __rhs._M_curr()
207 && __lhs._M_buf_index == __rhs._M_buf_index;
208 else if (__lhs._M_curr() != __rhs._M_curr())
209 return false;
210 else if (__lhs._M_buf_index == __rhs._M_buf_index
211 && __lhs._M_buf_last == __rhs._M_buf_last)
212 return true;
213 else
214 return __lhs._M_buf_index == __lhs._M_buf_last
215 && __rhs._M_buf_index == __rhs._M_buf_last;
216 }
217
218 [[nodiscard]]
219 friend constexpr bool
220 operator==(_Utf_iterator __lhs, _Sent __rhs)
221 {
222 if constexpr (forward_iterator<_Iter>)
223 return __lhs._M_curr() == __rhs;
224 else
225 return __lhs._M_curr() == __rhs
226 && __lhs._M_buf_index == __lhs._M_buf_last;
227 }
228
229 private:
230 constexpr void
231 _M_read()
232 {
233 if constexpr (sizeof(_FromFmt) == sizeof(uint8_t))
234 _M_read_utf8();
235 else if constexpr (sizeof(_FromFmt) == sizeof(uint16_t))
236 _M_read_utf16();
237 else
238 {
239 static_assert(sizeof(_FromFmt) == sizeof(uint32_t));
240 _M_read_utf32();
241 }
242 }
243
244 constexpr void
245 _M_read_reverse(); // TODO
246
247 template<typename>
248 struct _Guard
249 {
250 _Guard(void*, _Iter&) { }
251 };
252
253 template<typename _It> requires forward_iterator<_It>
254 struct _Guard<_It>
255 {
256 constexpr ~_Guard() { _M_this->_M_curr() = std::move(_M_orig); }
257 _Utf_iterator* _M_this;
258 _It _M_orig;
259 };
260
261 constexpr void
262 _M_read_utf8()
263 {
264 _Guard<_Iter> __g{this, _M_curr()};
265 char32_t __c{};
266 const uint8_t __lo_bound = 0x80, __hi_bound = 0xBF;
267 uint8_t __u = *_M_curr()++;
268 uint8_t __to_incr = 1;
269 auto __incr = [&, this] {
270 ++__to_incr;
271 return ++_M_curr();
272 };
273
274 if (__u <= 0x7F) [[likely]] // 0x00 to 0x7F
275 __c = __u;
276 else if (__u < 0xC2) [[unlikely]]
277 __c = _S_error();
278 else if (_M_curr() == _M_last) [[unlikely]]
279 __c = _S_error();
280 else if (__u <= 0xDF) // 0xC2 to 0xDF
281 {
282 __c = __u & 0x1F;
283 __u = *_M_curr();
284
285 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
286 __c = _S_error();
287 else
288 {
289 __c = (__c << 6) | (__u & 0x3F);
290 __incr();
291 }
292 }
293 else if (__u <= 0xEF) // 0xE0 to 0xEF
294 {
295 const uint8_t __lo_bound_2 = __u == 0xE0 ? 0xA0 : __lo_bound;
296 const uint8_t __hi_bound_2 = __u == 0xED ? 0x9F : __hi_bound;
297
298 __c = __u & 0x0F;
299 __u = *_M_curr();
300
301 if (__u < __lo_bound_2 || __u > __hi_bound_2) [[unlikely]]
302 __c = _S_error();
303 else if (__incr() == _M_last) [[unlikely]]
304 __c = _S_error();
305 else
306 {
307 __c = (__c << 6) | (__u & 0x3F);
308 __u = *_M_curr();
309
310 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
311 __c = _S_error();
312 else
313 {
314 __c = (__c << 6) | (__u & 0x3F);
315 __incr();
316 }
317 }
318 }
319 else if (__u <= 0xF4) // 0xF0 to 0xF4
320 {
321 const uint8_t __lo_bound_2 = __u == 0xF0 ? 0x90 : __lo_bound;
322 const uint8_t __hi_bound_2 = __u == 0xF4 ? 0x8F : __hi_bound;
323
324 __c = __u & 0x07;
325 __u = *_M_curr();
326
327 if (__u < __lo_bound_2 || __u > __hi_bound_2) [[unlikely]]
328 __c = _S_error();
329 else if (__incr() == _M_last) [[unlikely]]
330 __c = _S_error();
331 else
332 {
333 __c = (__c << 6) | (__u & 0x3F);
334 __u = *_M_curr();
335
336 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
337 __c = _S_error();
338 else if (__incr() == _M_last) [[unlikely]]
339 __c = _S_error();
340 else
341 {
342 __c = (__c << 6) | (__u & 0x3F);
343 __u = *_M_curr();
344
345 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
346 __c = _S_error();
347 else
348 {
349 __c = (__c << 6) | (__u & 0x3F);
350 __incr();
351 }
352 }
353 }
354 }
355 else [[unlikely]]
356 __c = _S_error();
357
358 _M_update(__c, __to_incr);
359 }
360
361 constexpr void
362 _M_read_utf16()
363 {
364 _Guard<_Iter> __g{this, _M_curr()};
365 char32_t __c{};
366 uint16_t __u = *_M_curr()++;
367 uint8_t __to_incr = 1;
368
369 if (__u < 0xD800 || __u > 0xDFFF) [[likely]]
370 __c = __u;
371 else if (__u < 0xDC00 && _M_curr() != _M_last)
372 {
373 uint16_t __u2 = *_M_curr();
374 if (__u2 < 0xDC00 || __u2 > 0xDFFF) [[unlikely]]
375 __c = _S_error();
376 else
377 {
378 ++_M_curr();
379 __to_incr = 2;
380 uint32_t __x = (__u & 0x3F) << 10 | (__u2 & 0x3FF);
381 uint32_t __w = (__u >> 6) & 0x1F;
382 __c = (__w + 1) << 16 | __x;
383 }
384 }
385 else
386 __c = _S_error();
387
388 _M_update(__c, __to_incr);
389 }
390
391 constexpr void
392 _M_read_utf32()
393 {
394 _Guard<_Iter> __g{this, _M_curr()};
395 char32_t __c = *_M_curr()++;
396 if (!__is_scalar_value(__c)) [[unlikely]]
397 __c = _S_error();
398 _M_update(__c, to_incr: 1);
399 }
400
401 // Encode the code point __c as one or more code units in _M_buf.
402 constexpr void
403 _M_update(char32_t __c, uint8_t __to_incr)
404 {
405 _M_to_increment = __to_incr;
406 _M_buf_index = 0;
407 if constexpr (sizeof(_ToFmt) == sizeof(uint32_t))
408 {
409 _M_buf[0] = __c;
410 _M_buf_last = 1;
411 }
412 else if constexpr (sizeof(_ToFmt) == sizeof(uint16_t))
413 {
414 if (__is_single_code_unit<_ToFmt>(__c))
415 {
416 _M_buf[0] = __c;
417 _M_buf[1] = 0;
418 _M_buf_last = 1;
419 }
420 else
421 {
422 // From http://www.unicode.org/faq/utf_bom.html#utf16-4
423 const char32_t __lead_offset = 0xD800 - (0x10000 >> 10);
424 char16_t __lead = __lead_offset + (__c >> 10);
425 char16_t __trail = 0xDC00 + (__c & 0x3FF);
426 _M_buf[0] = __lead;
427 _M_buf[1] = __trail;
428 _M_buf_last = 2;
429 }
430 }
431 else
432 {
433 static_assert(sizeof(_ToFmt) == 1);
434 int __bits = std::bit_width(x: (uint32_t)__c);
435 if (__bits <= 7) [[likely]]
436 {
437 _M_buf[0] = __c;
438 _M_buf[1] = _M_buf[2] = _M_buf[3] = 0;
439 _M_buf_last = 1;
440 }
441 else if (__bits <= 11)
442 {
443 _M_buf[0] = 0xC0 | (__c >> 6);
444 _M_buf[1] = 0x80 | (__c & 0x3F);
445 _M_buf[2] = _M_buf[3] = 0;
446 _M_buf_last = 2;
447 }
448 else if (__bits <= 16)
449 {
450 _M_buf[0] = 0xE0 | (__c >> 12);
451 _M_buf[1] = 0x80 | ((__c >> 6) & 0x3F);
452 _M_buf[2] = 0x80 | (__c & 0x3F);
453 _M_buf[3] = 0;
454 _M_buf_last = 3;
455 }
456 else
457 {
458 _M_buf[0] = 0xF0 | ((__c >> 18) & 0x07);
459 _M_buf[1] = 0x80 | ((__c >> 12) & 0x3F);
460 _M_buf[2] = 0x80 | ((__c >> 6) & 0x3F);
461 _M_buf[3] = 0x80 | (__c & 0x3F);
462 _M_buf_last = 4;
463 }
464 }
465 }
466
467 constexpr char32_t
468 _S_error()
469 {
470 char32_t __c = _ErrorHandler()();
471 __glibcxx_assert(__is_scalar_value(__c));
472 return __c;
473 }
474
475 constexpr _Iter
476 _M_first() const requires bidirectional_iterator<_Iter>
477 { return _M_first_and_curr._M_first; }
478
479 constexpr _Iter&
480 _M_curr() { return _M_first_and_curr._M_curr; }
481
482 constexpr _Iter
483 _M_curr() const { return _M_first_and_curr._M_curr; }
484
485 array<value_type, 4 / sizeof(_ToFmt)> _M_buf;
486
487 template<typename _It>
488 struct _First_and_curr
489 {
490 _First_and_curr() = default;
491
492 constexpr
493 _First_and_curr(_It __curr) : _M_curr(__curr) { }
494
495 template<convertible_to<_It> _It2>
496 constexpr
497 _First_and_curr(const _First_and_curr<_It2>& __other)
498 : _M_curr(__other._M_curr) { }
499
500 _It _M_curr;
501 };
502
503 template<typename _It> requires bidirectional_iterator<_It>
504 struct _First_and_curr<_It>
505 {
506 _First_and_curr() = default;
507
508 constexpr
509 _First_and_curr(_It __first, _It __curr)
510 : _M_first(__first), _M_curr(__curr) { }
511
512 template<convertible_to<_It> _It2>
513 constexpr
514 _First_and_curr(const _First_and_curr<_It2>& __other)
515 : _M_first(__other._M_first), _M_curr(__other._M_curr) { }
516
517 _It _M_first;
518 _It _M_curr;
519 };
520
521 _First_and_curr<_Iter> _M_first_and_curr;
522
523 uint8_t _M_buf_index = 0;
524 uint8_t _M_buf_last = 0;
525 uint8_t _M_to_increment = 0;
526
527 [[no_unique_address]] _Sent _M_last;
528
529 template<typename _FromFmt2, typename _ToFmt2,
530 input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
531 typename _ErrHandler>
532 requires convertible_to<iter_value_t<_Iter2>, _FromFmt2>
533 friend class _Utf_iterator;
534 };
535
536 template<typename _ToFormat, ranges::input_range _Range>
537 class _Utf_view
538 : public ranges::view_interface<_Utf_view<_ToFormat, _Range>>
539 {
540 using _Iterator = _Utf_iterator<ranges::range_value_t<_Range>,
541 _ToFormat, ranges::iterator_t<_Range>,
542 ranges::sentinel_t<_Range>>;
543
544 template<typename _Iter, typename _Sent>
545 constexpr auto
546 _M_begin(_Iter __first, _Sent __last)
547 {
548 if constexpr (bidirectional_iterator<_Iter>)
549 return _Iterator(__first, __first, __last);
550 else
551 return _Iterator(__first, __last);
552 }
553
554 template<typename _Iter, typename _Sent>
555 constexpr auto
556 _M_end(_Iter __first, _Sent __last)
557 {
558 if constexpr (!is_same_v<_Iter, _Sent>)
559 return __last;
560 else if constexpr (bidirectional_iterator<_Iter>)
561 return _Iterator(__first, __last, __last);
562 else
563 return _Iterator(__last, __last);
564 }
565
566 _Range _M_base;
567
568 public:
569 constexpr explicit
570 _Utf_view(_Range&& __r) : _M_base(std::forward<_Range>(__r)) { }
571
572 constexpr auto begin()
573 { return _M_begin(ranges::begin(_M_base), ranges::end(_M_base)); }
574
575 constexpr auto end()
576 { return _M_end(ranges::begin(_M_base), ranges::end(_M_base)); }
577
578 constexpr bool empty() const { return ranges::empty(_M_base); }
579 };
580
581#ifdef __cpp_char8_t
582 template<typename _View>
583 using _Utf8_view = _Utf_view<char8_t, _View>;
584#else
585 template<typename _View>
586 using _Utf8_view = _Utf_view<char, _View>;
587#endif
588 template<typename _View>
589 using _Utf16_view = _Utf_view<char16_t, _View>;
590 template<typename _View>
591 using _Utf32_view = _Utf_view<char32_t, _View>;
592
593inline namespace __v15_1_0
594{
595#define _GLIBCXX_GET_UNICODE_DATA 150100
596#include "unicode-data.h"
597#ifdef _GLIBCXX_GET_UNICODE_DATA
598# error "Invalid unicode data"
599#endif
600
601 // The field width of a code point.
602 constexpr int
603 __field_width(char32_t __c) noexcept
604 {
605 if (__c < __width_edges[0]) [[likely]]
606 return 1;
607
608 auto* __p = std::upper_bound(first: __width_edges, last: std::end(arr: __width_edges), val: __c);
609 return (__p - __width_edges) % 2 + 1;
610 }
611
612 // @pre c <= 0x10FFFF
613 constexpr _Gcb_property
614 __grapheme_cluster_break_property(char32_t __c) noexcept
615 {
616 constexpr uint32_t __mask = (1 << __gcb_shift_bits) - 1;
617 auto* __end = std::end(arr: __gcb_edges);
618 auto* __p = std::lower_bound(first: __gcb_edges, last: __end,
619 val: (__c << __gcb_shift_bits) | __mask);
620 return _Gcb_property(__p[-1] & __mask);
621 }
622
623 constexpr bool
624 __is_incb_linker(char32_t __c) noexcept
625 {
626 const auto __end = std::end(arr: __incb_linkers);
627 // Array is small enough that linear search is faster than binary search.
628 return std::find(first: __incb_linkers, last: __end, val: __c) != __end;
629 }
630
631 // @pre c <= 0x10FFFF
632 constexpr _InCB
633 __incb_property(char32_t __c) noexcept
634 {
635 if ((__c << 2) < __incb_edges[0]) [[likely]]
636 return _InCB(0);
637
638 constexpr uint32_t __mask = 0x3;
639 auto* __end = std::end(arr: __incb_edges);
640 auto* __p = std::lower_bound(first: __incb_edges, last: __end, val: (__c << 2) | __mask);
641 return _InCB(__p[-1] & __mask);
642 }
643
644 constexpr bool
645 __is_extended_pictographic(char32_t __c)
646 {
647 if (__c < __xpicto_edges[0]) [[likely]]
648 return 0;
649
650 auto* __p = std::upper_bound(first: __xpicto_edges, last: std::end(arr: __xpicto_edges), val: __c);
651 return (__p - __xpicto_edges) % 2;
652 }
653
654 struct _Grapheme_cluster_iterator_base
655 {
656 char32_t _M_c; // First code point in the cluster.
657 _Gcb_property _M_prop; // GCB property of _M_c.
658 enum class _XPicto : unsigned char { _Init, _Zwj, _Matched, _Failed };
659 _XPicto _M_xpicto_seq_state = _XPicto::_Init;
660 unsigned char _M_RI_count = 0;
661 bool _M_incb_linker_seen = false;
662
663 constexpr void
664 _M_reset(char32_t __c, _Gcb_property __p)
665 {
666 _M_c = __c;
667 _M_prop = __p;
668 _M_xpicto_seq_state = _XPicto::_Init;
669 _M_RI_count = 0;
670 _M_incb_linker_seen = false;
671 }
672
673 constexpr void
674 _M_update_xpicto_seq_state(char32_t __c, _Gcb_property __p)
675 {
676 if (_M_xpicto_seq_state == _XPicto::_Failed)
677 return;
678
679 auto __next_state = _XPicto::_Failed;
680 if (_M_xpicto_seq_state != _XPicto::_Zwj) // i.e. Init or Matched
681 {
682 if (__p == _Gcb_property::_Gcb_ZWJ)
683 {
684 if (_M_xpicto_seq_state == _XPicto::_Matched)
685 __next_state = _XPicto::_Zwj;
686 // We check _M_c here so that we do the lookup at most once,
687 // and only for clusters containing at least one ZWJ.
688 else if (__is_extended_pictographic(c: _M_c))
689 __next_state = _XPicto::_Zwj;
690 }
691 else if (__p == _Gcb_property::_Gcb_Extend)
692 __next_state = _M_xpicto_seq_state; // no change
693 }
694 else // Zwj
695 {
696 // This assumes that all \p{Extended_Pictographic} emoji have
697 // Grapheme_Cluster_Break=Other.
698 if (__p == _Gcb_property::_Gcb_Other
699 && __is_extended_pictographic(__c))
700 __next_state = _XPicto::_Matched;
701 }
702 _M_xpicto_seq_state = __next_state;
703 }
704
705 constexpr void
706 _M_update_ri_count(_Gcb_property __p)
707 {
708 if (__p == _Gcb_property::_Gcb_Regional_Indicator)
709 ++_M_RI_count;
710 else
711 _M_RI_count = 0;
712 }
713
714 constexpr void
715 _M_update_incb_state(char32_t __c, _Gcb_property)
716 {
717 if (__is_incb_linker(__c))
718 _M_incb_linker_seen = true;
719 }
720 };
721
722 // Split a range into extended grapheme clusters.
723 template<ranges::forward_range _View> requires ranges::view<_View>
724 class _Grapheme_cluster_view
725 : public ranges::view_interface<_Grapheme_cluster_view<_View>>
726 {
727 public:
728
729 constexpr
730 _Grapheme_cluster_view(_View __v)
731 : _M_begin(_Utf32_view<_View>(std::move(__v)).begin())
732 { }
733
734 constexpr auto begin() const { return _M_begin; }
735 constexpr auto end() const { return _M_begin.end(); }
736
737 private:
738 struct _Iterator : private _Grapheme_cluster_iterator_base
739 {
740 private:
741 // Iterator over the underlying code points.
742 using _U32_iterator = ranges::iterator_t<_Utf32_view<_View>>;
743
744 public:
745 // TODO: Change value_type to be subrange<_U32_iterator> instead?
746 // Alternatively, value_type could be _Utf32_view<iterator_t<_View>>.
747 // That would be the whole cluster, not just the first code point.
748 // Would need to store two iterators and find end of current cluster
749 // on increment, so operator* returns value_type(_M_base, _M_next).
750 using value_type = char32_t;
751 using iterator_concept = forward_iterator_tag;
752 using difference_type = ptrdiff_t;
753
754 constexpr
755 _Iterator(_U32_iterator __i)
756 : _M_base(__i)
757 {
758 if (__i != __i.end())
759 {
760 _M_c = *__i;
761 _M_prop = __grapheme_cluster_break_property(_M_c);
762 }
763 }
764
765 // The first code point of the current extended grapheme cluster.
766 constexpr value_type
767 operator*() const
768 { return _M_c; }
769
770 constexpr auto
771 operator->() const
772 { return &_M_c; }
773
774 // Move to the next extended grapheme cluster.
775 constexpr _Iterator&
776 operator++()
777 {
778 const auto __end = _M_base.end();
779 if (_M_base != __end)
780 {
781 auto __p_prev = _M_prop;
782 auto __it = _M_base;
783 while (++__it != __end)
784 {
785 char32_t __c = *__it;
786 auto __p = __grapheme_cluster_break_property(*__it);
787 _M_update_xpicto_seq_state(__c, __p);
788 _M_update_ri_count(__p);
789 _M_update_incb_state(__c, __p);
790 if (_M_is_break(p1: __p_prev, p2: __p, curr: __it))
791 {
792 // Found a grapheme cluster break
793 _M_reset(__c, __p);
794 break;
795 }
796 __p_prev = __p;
797 }
798 _M_base = __it;
799 }
800 return *this;
801 }
802
803 constexpr _Iterator
804 operator++(int)
805 {
806 auto __tmp = *this;
807 ++*this;
808 return __tmp;
809 }
810
811 constexpr bool
812 operator==(const _Iterator& __i) const
813 { return _M_base == __i._M_base; }
814
815 // This supports iter != iter.end()
816 constexpr bool
817 operator==(const ranges::sentinel_t<_View>& __i) const
818 { return _M_base == __i; }
819
820 // Iterator to the start of the current cluster.
821 constexpr auto base() const { return _M_base.base(); }
822
823 // The end of the underlying view (not the end of the current cluster!)
824 constexpr auto end() const { return _M_base.end(); }
825
826 // Field width of the first code point in the cluster.
827 constexpr int
828 width() const noexcept
829 { return __field_width(_M_c); }
830
831 private:
832 _U32_iterator _M_base;
833
834 // Implement the Grapheme Cluster Boundary Rules from Unicode Annex #29
835 // http://www.unicode.org/reports/tr29/#Grapheme_Cluster_Boundary_Rules
836 // This implements the rules from TR29 revision 43 in Unicode 15.1.0.
837 // Return true if there is a break between code point with property p1
838 // and code point with property p2.
839 constexpr bool
840 _M_is_break(_Gcb_property __p1, _Gcb_property __p2,
841 _U32_iterator __curr) const
842 {
843 using enum _Gcb_property;
844
845 if (__p1 == _Gcb_Control || __p1 == _Gcb_LF)
846 return true; // Break after Control or LF.
847
848 if (__p1 == _Gcb_CR)
849 return __p2 != _Gcb_LF; // Do not break between a CR and LF.
850
851 // Rule GB5
852 if (__p2 == _Gcb_Control || __p2 == _Gcb_CR || __p2 == _Gcb_LF)
853 return true; // Break before Control, CR or LF.
854
855 // Rule GB6
856 if (__p1 == _Gcb_L)
857 switch (__p2)
858 {
859 case _Gcb_L:
860 case _Gcb_V:
861 case _Gcb_LV:
862 case _Gcb_LVT:
863 return false; // Do not break Hangul syllable sequences.
864 default:
865 return true;
866 }
867
868 // Rule GB7
869 if (__p1 == _Gcb_LV || __p1 == _Gcb_V)
870 switch (__p2)
871 {
872 case _Gcb_V:
873 case _Gcb_T:
874 return false; // Do not break Hangul syllable sequences.
875 default:
876 return true;
877 }
878
879 // Rule GB8
880 if (__p1 == _Gcb_LVT || __p1 == _Gcb_T)
881 return __p2 != _Gcb_T; // Do not break Hangul syllable sequences.
882
883 // Rule GB9
884 if (__p2 == _Gcb_Extend || __p2 == _Gcb_ZWJ)
885 return false; // Do not break before extending characters or ZWJ.
886
887 // The following GB9x rules only apply to extended grapheme clusters,
888 // which is what the C++ standard uses (not legacy grapheme clusters).
889
890 // Rule GB9a
891 if (__p2 == _Gcb_SpacingMark)
892 return false; // Do not break before SpacingMarks,
893 // Rule GB9b
894 if (__p1 == _Gcb_Prepend)
895 return false; // or after Prepend characters.
896
897 // Rule GB9c (Unicode 15.1.0)
898 // Do not break within certain combinations with
899 // Indic_Conjunct_Break (InCB)=Linker.
900 if (_M_incb_linker_seen
901 && __incb_property(_M_c) == _InCB::_Consonant
902 && __incb_property(*__curr) == _InCB::_Consonant)
903 {
904 // Match [_M_base, __curr] against regular expression
905 // Consonant ([Extend Linker]* Linker [Extend Linker]* Consonant)+
906 bool __have_linker = false;
907 auto __it = _M_base;
908 while (++__it != __curr)
909 {
910 if (__is_incb_linker(*__it))
911 __have_linker = true;
912 else
913 {
914 auto __incb = __incb_property(*__it);
915 if (__incb == _InCB::_Consonant)
916 __have_linker = false;
917 else if (__incb != _InCB::_Extend)
918 break;
919 }
920 }
921 if (__it == __curr && __have_linker)
922 return false;
923 }
924
925 // Rule GB11
926 // Do not break within emoji modifier sequences
927 // or emoji zwj sequences.
928 if (__p1 == _Gcb_ZWJ && _M_xpicto_seq_state == _XPicto::_Matched)
929 return false;
930
931 // Rules GB12 and GB13
932 // Do not break within emoji flag sequences. That is, do not break
933 // between regional indicator (RI) symbols if there is an odd number
934 // of RI characters before the break point.
935 if (__p1 == _Gcb_property::_Gcb_Regional_Indicator && __p1 == __p2)
936 return (_M_RI_count & 1) == 0;
937
938 // Rule GB999
939 return true; // Otherwise, break everywhere.
940 }
941 };
942
943 _Iterator _M_begin;
944 };
945
946} // namespace __v15_1_0
947
948 // Return the field width of a string.
949 template<typename _CharT>
950 constexpr size_t
951 __field_width(basic_string_view<_CharT> __s)
952 {
953 if (__s.empty()) [[unlikely]]
954 return 0;
955 _Grapheme_cluster_view<basic_string_view<_CharT>> __gc(__s);
956 auto __it = __gc.begin();
957 const auto __end = __gc.end();
958 size_t __n = __it.width();
959 while (++__it != __end)
960 __n += __it.width();
961 return __n;
962 }
963
964 // Truncate a string to at most `__max` field width units, and return the
965 // resulting field width.
966 template<typename _CharT>
967 constexpr size_t
968 __truncate(basic_string_view<_CharT>& __s, size_t __max)
969 {
970 if (__s.empty()) [[unlikely]]
971 return 0;
972
973 _Grapheme_cluster_view<basic_string_view<_CharT>> __gc(__s);
974 auto __it = __gc.begin();
975 const auto __end = __gc.end();
976 size_t __n = __it.width();
977 if (__n > __max)
978 {
979 __s = {};
980 return 0;
981 }
982 while (++__it != __end)
983 {
984 size_t __n2 = __n + __it.width();
985 if (__n2 > __max)
986 {
987 __s = basic_string_view<_CharT>(__s.begin(), __it.base());
988 return __n;
989 }
990 __n = __n2;
991 }
992 return __n;
993 }
994
995 template<typename _CharT>
996 consteval bool
997 __literal_encoding_is_unicode()
998 {
999 if constexpr (is_same_v<_CharT, char16_t>)
1000 return true;
1001 else if constexpr (is_same_v<_CharT, char32_t>)
1002 return true;
1003#ifdef __cpp_char8_t
1004 else if constexpr (is_same_v<_CharT, char8_t>)
1005 return true;
1006#endif
1007
1008 const char* __enc = "";
1009
1010#ifdef __GNUC_EXECUTION_CHARSET_NAME
1011 auto __remove_iso10646_prefix = [](const char* __s) {
1012 // GNU iconv allows "ISO-10646/" prefix (case-insensitive).
1013 if (__s[0] == 'I' || __s[0] == 'i')
1014 if (__s[1] == 'S' || __s[1] == 's')
1015 if (__s[2] == 'O' || __s[2] == 'o')
1016 if (string_view(__s + 3).starts_with("-10646/"))
1017 return __s + 10;
1018 return __s;
1019 };
1020
1021 if constexpr (is_same_v<_CharT, char>)
1022 __enc = __remove_iso10646_prefix(__GNUC_EXECUTION_CHARSET_NAME);
1023# if defined _GLIBCXX_USE_WCHAR_T && defined __GNUC_WIDE_EXECUTION_CHARSET_NAME
1024 else
1025 __enc = __remove_iso10646_prefix(__GNUC_WIDE_EXECUTION_CHARSET_NAME);
1026# endif
1027
1028 if ((__enc[0] == 'U' || __enc[0] == 'u')
1029 && (__enc[1] == 'T' || __enc[1] == 't')
1030 && (__enc[2] == 'F' || __enc[2] == 'f'))
1031 {
1032 __enc += 3;
1033 if (__enc[0] == '-')
1034 ++__enc;
1035 if (__enc[0] == '8')
1036 return __enc[1] == '\0' || string_view(__enc + 1) == "//";
1037 else if constexpr (!is_same_v<_CharT, char>)
1038 {
1039 string_view __s(__enc);
1040 if (__s.ends_with("//"))
1041 __s.remove_suffix(2);
1042 return __s == "16" || __s == "32";
1043 }
1044 }
1045#elif defined __clang_literal_encoding__
1046 if constexpr (is_same_v<_CharT, char>)
1047 __enc = __clang_literal_encoding__;
1048# if defined _GLIBCXX_USE_WCHAR_T && defined __clang_wide_literal_encoding__
1049 else
1050 __enc = __clang_wide_literal_encoding__;
1051# endif
1052 // Clang accepts "-fexec-charset=utf-8" but the macro is still uppercase.
1053 string_view __s(__enc);
1054 if (__s == "UTF-8")
1055 return true;
1056 else if constexpr (!is_same_v<_CharT, char>)
1057 return __s == "UTF-16" || __s == "UTF-32";
1058#endif
1059
1060 return false;
1061 }
1062
1063 consteval bool
1064 __literal_encoding_is_utf8()
1065 { return __literal_encoding_is_unicode<char>(); }
1066
1067 consteval bool
1068 __literal_encoding_is_extended_ascii()
1069 {
1070 return '0' == 0x30 && 'A' == 0x41 && 'Z' == 0x5a
1071 && 'a' == 0x61 && 'z' == 0x7a;
1072 }
1073
1074 // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
1075 constexpr bool
1076 __charset_alias_match(string_view __a, string_view __b)
1077 {
1078 // Map alphanumeric chars to their base 64 value, everything else to 127.
1079 auto __map = [](char __c, bool& __num) -> unsigned char {
1080 if (__c == '0') [[unlikely]]
1081 return __num ? 0 : 127;
1082 const auto __v = __detail::__from_chars_alnum_to_val(__c);
1083 __num = __v < 10;
1084 return __v;
1085 };
1086
1087 auto __ptr_a = __a.begin(), __end_a = __a.end();
1088 auto __ptr_b = __b.begin(), __end_b = __b.end();
1089 bool __num_a = false, __num_b = false;
1090
1091 while (true)
1092 {
1093 // Find the value of the next alphanumeric character in each string.
1094 unsigned char __val_a{}, __val_b{};
1095 while (__ptr_a != __end_a
1096 && (__val_a = __map(*__ptr_a, __num_a)) == 127)
1097 ++__ptr_a;
1098 while (__ptr_b != __end_b
1099 && (__val_b = __map(*__ptr_b, __num_b)) == 127)
1100 ++__ptr_b;
1101 // Stop when we reach the end of a string, or get a mismatch.
1102 if (__ptr_a == __end_a)
1103 return __ptr_b == __end_b;
1104 else if (__ptr_b == __end_b)
1105 return false;
1106 else if (__val_a != __val_b)
1107 return false; // Found non-matching characters.
1108 ++__ptr_a;
1109 ++__ptr_b;
1110 }
1111 return true;
1112 }
1113
1114} // namespace __unicode
1115
1116namespace ranges
1117{
1118 template<typename _To, typename _Range>
1119 inline constexpr bool
1120 enable_borrowed_range<std::__unicode::_Utf_view<_To, _Range>>
1121 = enable_borrowed_range<_Range>;
1122
1123 template<typename _Range>
1124 inline constexpr bool
1125 enable_borrowed_range<std::__unicode::_Grapheme_cluster_view<_Range>>
1126 = enable_borrowed_range<_Range>;
1127} // namespace ranges
1128
1129_GLIBCXX_END_NAMESPACE_VERSION
1130} // namespace std
1131#endif // C++20
1132#endif // _GLIBCXX_UNICODE_H
1133